Abstract

The difference of the resolvents of two Laplacians on a half-space subject to Robin boundary conditions is studied.In general this difference is not compact, but it will be shown that it is compact and even belongs to some Schatten-von Neumann class, if the coefficients in the boundary condition are sufficiently close to each other in a proper sense.I n certain cases the resolvent difference is shown to belong even to the same Schatten-von Neumann class as it is known for the resolvent difference of two Robin Laplacians on a domain with a compact boundary.